Mitsubishi Lancer Evolution IX. Manual - part 444

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-251

STEP 11. Check harness between C-01 (terminal 
No. 17) combination connector and C-121 
(terminal No. 22) engine-ECU connector.

NOTE: Before checking harness, check intermediate 
connector C-124, and repair if necessary.

• Check output line for damage.

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Repair the damaged harness wire.

STEP 12. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace the engine-ECU.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

AK301236

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Harness side connector

Connector: C-01

C-01

<L. H. drive vehicles>

<R. H. drive vehicles>

C-01 

AC

AK501995

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AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-252

Inspection Procedure 4: The Engine Warning Lamp Remains Illuminating and never goes out

AK501825

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R

IG2

ST

LOCK

ACC

IG1

2

7.5A

6

C-211

25

C-214

Ignition switch

C-208

2

B-W

Y-R

O

Y-R

W-L

W-L

19

17

J/B

C-01

Engine-ECU

9

22

Engine warning lamp (check engine lamp) circuit

Engine warning lamp (check engine lamp)

9

17

Wire colour code
B: Black  LG: Light green  G: Green  L: Blue  W: White  Y: Yellow  SB: Sky blue  BR: Brown  O: Orange  GR: Gray
R: Red  P: Pink  V: Violet  PU: Purple

AB

C-121

(MU803784)

NOTE

*1: L.H. drive vehicles
*2: R.H. drive vehicles

*1

*2

J/C (4)
C-23

Chec

k

engine

C-124

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-253

OPERATION

• Battery voltage is applied to engine warning lamp 

(terminal No. 9) from ignition switch.

• Engine-ECU (terminal No. 22) makes power tran-

sistor in unit be in "ON" position, and that makes 
currents go on engine warning lamp (terminal No. 
17).

COMMENTS ON TROUBLE SYMPTOM

• Engine-ECU has detected failed sensor or failed 

actuator. Or failure is possibly caused by short 
circuit or other faults.

PROBABLE CAUSES

• Short circuit in between engine warning lamp and 

engine-ECU circuit.

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III diagnosis code

Q: Diagnosis code set?

YES : 

Inspection chart for diagnosis code (Refer 

to 

P.13A-17

).

NO : 

Go to Step 2 .

STEP 2. Connector check: C-121 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

AK501995

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AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-254

STEP 3. Perform voltage measurement at C-121 
engine-ECU connector.

• Disconnect connector, and measure at the har-

ness side.

• Ignition switch: "ON"

• Voltage between terminal No. 22 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check intermediate connector C-124, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between C-01 (terminal No. 17) 
combination meter connector and C-121 
(terminal No. 22) engine-ECU connector.

• Check output line for short circuit.

STEP 4. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Replace the engine-ECU.

NO : 

Intermittent malfunction (Refer to GROUP 
00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

AK501995

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AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK301236

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Harness side connector

Connector: C-01

C-01

<L. H. drive vehicles>

<R. H. drive vehicles>

C-01 

AC